Atherectomy catheter with laterally-displaceable tip

ABSTRACT

Described herein are atherectomy catheters, systems and methods that include a distal tip region that may be moved laterally so that its long axis is parallel with the long axis of the main catheter body axis. Displacing the distal tip region laterally out of the main catheter body axis exposes an annular blade and opens a passageway for cut tissue to enter a storage region within the catheter. The annular blade may be internally coupled to a drive shaft that rotates the blade, and thus the exposed blade edge may have the same crossing profile (OD) as the rest of the distal end region of the catheter. Also described herein are gear-driven atherectomy devices that may use a cable drive shaft to actuate the annular blade. Both push-to-cut and pull-to-cut variations are described, as are methods for cutting tissue and systems including these atherectomy catheters.

CROSS REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation of U.S. patent applicationSer. No. 12/829,277, filed Jul. 1, 2010, titled “ATHERECTOMY CATHETERWITH LATERALLY-DISPLACEABLE TIP,” now U.S. Pat. No. 9,498,600, whichclaims priority to U.S. Provisional Patent Application No. 61/222,242,titled “GEAR DRIVEN ATHERECTOMY CATHETER” filed on Jul. 1, 2009.

This application may also be related to U.S. patent application Ser. No.12/790,703, titled “OPTICAL COHERENCE TOMOGRAPHY FOR BIOLOGICALIMAGING,” filed on May 28, 2010.

INCORPORATION BY REFERENCE

All publications and patent applications mentioned in this specificationare herein incorporated by reference in their entirety to the sameextent as if each individual publication or patent application wasspecifically and individually indicated to be incorporated by reference.

FIELD OF THE INVENTION

Described herein are atherectomy catheters with laterally displaceabletips, systems including such catheters and methods of using them.

BACKGROUND OF THE INVENTION

A significant body of scientific and clinical evidence supportsatherectomy as a viable primary or adjunctive therapy prior to stentingfor the treatment of occlusive coronary artery disease. Atherectomyoffers a simple mechanical advantage over alternative therapies. Byremoving the majority of plaque mass (debulking) it creates a largerinitial lumen and dramatically increases the compliance of the arterialwall. As a result, stent deployment is greatly enhanced.

Additionally, there are advantages related to the arterial healingresponse. When circumferential radial forces are applied to thevasculature, as in the case of angioplasty or stenting, the plaque massis displaced, forcing the vessel wall to stretch dramatically. Thisstretch injury is a known stimulus for the cellular in-growth that leadsto restenosis. By removing the disease with minimal force applied to thevessel and reducing the plaque burden prior to stent placement, largegains in lumen size can be created with decreased vessel wall injury andlimited elastic recoil which have shown to translate into better acuteresults and lower restenosis rates.

Traditional atherectomy devices have been plagued by a number ofproblems, which have severely limited market adoption. These challengesinclude the need for large access devices, rigid distal assemblies thatmake control and introduction challenging, fixed cut length,unpredictable depth of cut, insufficient tissue collection and removal,and complex operation. The systems and devices described herein mayovercome these hurdles and offer physicians a safe, reliable, and simplecutting system that offers the precision required in eccentric lesions,various disease states, and tortuous anatomy.

Despite the potential to improve restenosis rates associated withangioplasty and stenting in the coronary and peripheral vasculature,atherectomy is not commonly performed. The primary reason for thislimited use is the cost, complexity and limited applicability ofcurrently available devices. Many designs are unable to treat the widerange of disease states present in long complex lesions; luminal gain isoften limited by the requirement of the physician to introduce multipledevices with increased crossing profiles; tissue collection is eitherunpredictable or considered unnecessary based on assumptions regardingsmall particle size and volumes; and optimal debulking is either notpossible due to lack of intravascular visualization or requires verylong procedure times. Based on these limitations current devices arelikely to perform poorly in the coronary vasculature where safety andefficacy in de novo lesions, ostials, and bifurcations continue to posegreat challenges.

Previously, atherectomy devices focused on macerating or emulsifying theatherosclerotic plaque such that it may be considered clinicallyinsignificant and remain in the blood stream or aspirated proximallythrough small spaces in the catheter main body. The reliability of thesedevices to produce clinically insignificant embolization has beenquestioned when not aspirated through the catheter to an externalreservoir. Aspiration requires a vacuum be applied to a lumen or annularspace within the catheter to remove emulsified tissue. In early clinicalevaluations of aspiration the presence of negative pressure at thedistal working assembly cause the artery to collapse around the cuttingelement causing more aggressive treatment, dissections and/orperforations. In addition, the option for post procedural analysis ofany removed disease is extremely limited or impossible. Atheromed,Pathway Medical and Cardio Vascular Systems, Inc. are examples ofcompanies working on such product designs.

Other atherectomy devices include the directional atherectomy devicessuch as those developed by DVI and FoxHollow. These catheters use cuppedcutters that cut and “turn” the tissue distal into a storage reservoirin the distal tip of the device. This approach preserves the “as cut”nature of the plaque but requires large distal collection elements.These large distal tip assemblies can limit the capabilities of thesystem to access small lesions and create additional trauma to thevessel.

Currently available atherectomy devices also do not include, and arepoorly adapted for use with, real time image guidance. Physicianpractice is often to treat target lesion as if they contain concentricdisease even though intravascular diagnostic devices have consistentlyshown significantly eccentric lesions. This circumferential treatmentapproach virtually ensures that native arterial wall and potentiallyhealthy vessel will be cut from the vasculature.

Atherectomy catheter devices, systems and methods that may address someof these concerns are described and illustrated below.

SUMMARY OF THE INVENTION

Described herein are atherectomy catheters, systems including them andmethods of using them. Some of the distinguishing features that may beincluded as part of these devices, systems and methods are summarizedbelow.

In general the atherectomy devices described herein include laterallydisplaceable distal tip regions. Lateral displacement of the distal tipregion typically means that the longitudinal axis of the distal tipregion is radially displaced relative to the longitudinal axis of thedistal end of the rest of the catheter body. Longitudinal displacementof the distal tip region effectively drops the distal tip region awayfrom the rest of the catheter body, and may expose one or more cuttingregions on or in the catheter, and provide an opening into which cuttissue may enter for storage and/or removal.

In some variations, the catheters described herein include an annularcutting ring or element having at least one cutting edge. An annularcutting ring may be a cylindrical element (or a partial cylinder) thathas at least one sharpened or cutting edge. The sharp/cutting edge maybe sharp, tapered, serrated, or otherwise configured to cut into tissuessuch as those within a diseased lumen of a vessel. The annular cuttingedge may be rotatable, typically rotating about a long axis that isparallel to the direction of cutting (i.e., the longitudinal axis of thecatheter). The cutting edge of the annular cutting ring may be locatedalong one edge, such as the circular lip of a cylindrical-shaped annularcutting ring.

In some variations, the annular cutting ring includes one or moreoutwardly-facing non-cutting sides. The outwardly-facing side(s) of theannular cutting ring may form an external surface of the catheter. Insome variations the annular cutting ring is approximately the width ofthe catheter, which may maximize the size of the cutting edge of theannular cutting ring.

Any of the devices described herein may be gear-driven, and may includea gear driven distal assembly that may provide additional flexibilityfor locating a cutter driving element at or near the distal end of thecatheter. Annular cutting rings that are driven by a geared driveshaftmay offer mechanical advantages compared to annular cutters driven by arotating driveshaft that is concentric to, and housed within, the mainbody of the catheter shaft. Driveshafts that are directly coupled to thecutter blade may be driven with standard DC motors, hydraulics orpneumatics. However, the concentric configuration may limit the spaceproximal to the cutting element available for proximal tissue storageand/or removal. The catheter described herein may include bothgear-driven and directly-coupled driveshaft embodiments.

The mechanical advantage provided by the geared cutting assembliesdescribed herein also provides additional design options for the cuttingmechanisms. This approach would require lower input torque anddriveshaft performance requirements necessary to power a cutter throughvery hard calcified lesions. Different gear ratios may be used indesigns intended to cut soft tissue or hard disease. It is also possiblefor multiple gear ratios to be provided in one device to be modified bythe physician as deemed necessary.

Any of the atherectomy catheters described herein may also be used tocut and store tissue for later analysis and/or for removal from thebody. For example, the devices described herein may include a primaryhollow cutter and internal gear driven configuration that may allowtissue to travel directly through the cutter, from distal to proximal,once planed from the arterial wall and be stored proximal to the cutterin its “as cut” state, allowing for future histological evaluations. Insome variations, the gearing means and direction of distal tip motionwhen activating the cutter may ensure appropriate position of appositionforce for the cutter to engage tissue.

The laterally displaceable distal tip regions may help ensure closelongitudinal proximity of the cutting edge (e.g., a proximal tip edge)or tissue shearing edge, to the wall of the vessel and reliably link theamount of cutter exposure to the depth of cut independent of the amountof cutter apposition force.

The laterally displaceable distal tip assembly may be displaceabledirectly downward, preserving parallel alignment of the tip and cathetershaft axis, and providing efficient use of energy sources for simplifieddevice actuation and manipulation. The lateral displacement may alsoallow intravascular imaging elements located on the distal assembly ofthe device to provide real time diagnostic information to physician.

Guided atherectomy systems are described herein. These devices areintended to access the vasculature using conventional catheterizationtechniques employing sheath and/or guiding catheter access and trackingover a positioned pre-positioned guidewire. The atherectomy devicesdescribed herein may be adapted for use with a guidewire or sheath. Forexample, the atherectomy catheter may include a central guidewire lumen.The catheters described herein may generally track through thevasculature to the target lesion.

In some variations, the devices include visualization, and particularlyOptical Coherence Tomography (OCT) image visualization. For example, insome variations, a fiber affixed or positioned at or near the distalassembly of the device and extending proximally will enable OCT imagingto be used for lesion assessment and treatment planning. In use, thedevice may be rotationally oriented toward the diseased sector of theartery, and the device may be activated using proximal physiciancontrols so that the distal tip assembly will laterally displace (e.g.,moving away from the cutter) to expose the cutting edge to the diseasedtissue. The annular cutter may be rotated, e.g., at approximately 100 to10000 rpm. The device may then be translated through the lesion to planeand cut the diseased tissue while the OCT image provides real timefeedback regarding wall and disease characteristics, cutter appositionand cut depth. During a cutting pass, the tissue may feed into thecatheter and travel through the hollow cutter and into a proximal tissuereservoir. Upon completing the cutting pass, the proximal controls maybe used to deactivate the device, closing the tip against the spinningcutter and terminating the planed tissue with a scissoring action andstopping cutter rotation. Multiple runs through this procedure may occurto fully treat the disease.

Atherectomy catheters and systems using them may have a cutter (e.g.,the cutting edge of an annular cutting ring) diameter at or near themaximum crossing profile of the main catheter body, which may maximizecut tissue cross-sectional area, and minimize the depth of cut. Thelarge cross-sectional area may reduce the procedure time, providing moreefficient cutting passes and add a degree of safety by reducing thedepth of cut required to achieve these efficiencies. The depth of thecut may be controlled by the lateral displacement of the distal end ofthe device, which both determines the opening size and how much of thecutter is exposed, and may also drive the cutter against the wall of thevessel by effectively widening the device within the vessel lumen.

The hollow cutters (annular cutting rings) described may allow tissue tobe cut from the wall of the artery, pass directly through the catheter,and be stored in a reservoir. Both forward-cutting (push-cuttingdevices) and reverse (pull) cutting devices are described. Inpull-cutting devices, the tissue may preferentially be stored distally,which in push cutting devices, the tissue may be preferentially bestored proximally. In some variations a deflector or guide may be usedto direct the cut tissue into a proximal and/or distal storage areawithin the device. Proximal tissue storage may allow the distal tipregion diameters and lengths to be reduced. Reduced tip dimensions mayhelp the device cross tight lesions, cut in quickly tapering vessels,and generally be less traumatic to downstream vascular structures.

In variations including an internal gear driven cutter, the annularcutting ring may include female gears on the cutter body internaldiameter. This may provide a large, mainly centralized, region fortissue to pass through the cutter and into a proximal storage area, asmentioned. The gear mechanism may also provide a mechanical advantage tothe cutting assembly. In the embodiments described below, the inputtorque applied to the input pinion drive shaft may be 0.5× of thatrequired by a direct drive system to cut hard/calcified disease. Thedriveshaft may balance flexibility to navigate tortuous anatomy andtorsional/tensile/compressive rigidity to drive distal mechanismsthrough hard calcium or tight lesions. The mechanical advantage of theinternal gear drive may provide more options for driveshaft design. Inaddition, an internal gear may help achieve better engagement of microscale tooth profiles. Fabrication of gears of this scale can bechallenging, and the increased tooth engagement of the internal gearconfiguration may limit wear of the materials and increase toothengagement leading to longer life and more consistent torque output andshock absorption.

The tissue entry window is mainly defined by the vertical distance fromouter tip diameter to cutter edge, which may minimize longitudinalmotion and reduce angular deflection of the tip mechanism. As mentioned,the depth of the cut may remain relatively constant at varied force ofengagement between cutter and tissue because of the lateral displacementof the distal tip region.

As mentioned, any of the variations described herein may includeon-board imaging with one or more imaging elements providing across-sectional view of vessel wall morphology in the cutting plane. Forexample, ultrasound and/or optical imaging technologies may be used. Inparticular, OCT imaging may be used. In some variations, the OCT imagingsystem may achieve around 10 micron lateral resolution and use opticalfibers having diameters below 0.010″.

In some variations of the cutter assemblies described herein, theannular cutting ring and the laterally displaceable distal tip allowconsistent cut depths even with high apposition forces. Angiography andintravascular imaging technologies may be used and a known depth of cutmay be overlaid on known depth of disease. Typically, the appositionforce applied may directly correlate to the vessel diameter and to thelevel of stenosis, reducing the potential for barotrauma and overtreatment.

In some variations, the catheter device also includes a handle havingone or more controls for controlling the catheter. For example, thesystem or device may include a handle having a control for laterallydisplacing the distal tip region and exposing the cutting edge of theannular cutting ring. Any appropriate control may be used, including abutton, switch, slider, knob, etc. The lateral displacement may becontrolled by a mechanical, electrical, and/or magnetic means. Forexample, an elongate tendon member (e.g., wire) which may be flexiblemay extend through the catheter body from proximal to distal ends toactuate the lateral displacement.

In addition, the devices or systems may also include one or morecontrols for controlling the rotation of the annular cutting ring.Rotation may be linked to the lateral displacement so that the cutterbegins rotating either shortly before or after lateral displacementexposes the cutter. Alternatively, the rotation may be independent ofthe lateral displacement. The devices or systems may also includecontrols for an associate imaging (e.g., OCT) system. In some variationsthe device or system includes control logic for regulating thedisplacement and/or rotation and/or imaging. Proximal controls mayinclude an automated advancement function to ensure proximal motioncorrelates to distal tracking in the vessel. In some variations, some orall of these controls may be on a handle, or may be on a separatecontroller.

Force limiting controls may also be used to ensure the input forces donot exceed what is required to effectively cut diseased tissue. This mayreduce the chances of the device moving outside the perimeter of thelesion while activated thereby cutting into healthy arterial wall.

In some variations, the catheter systems described herein are compatiblewith 7F sheath access to the peripheral arteries, or 6F sheath sizes.

For example, described herein are atherectomy catheters for cuttingtissue having a laterally displaceable tip. These devices may include:an elongate, flexible catheter body having a proximal end and a distalend and a longitudinal axis; an elongate and laterally displaceabledistal tip assembly; a rotatable annular cutting ring between the distalend of the catheter body and the distal tip assembly; and a distal tipcontrol at the proximal end of the catheter that is configured to exposea cutting edge of the annular cutting ring by laterally displacing thedistal tip assembly from a closed configuration in which the distal tipassembly is in-line with the catheter body, to an open configuration inwhich the distal tip assembly is laterally displaced from the catheterbody and parallel to the longitudinal axis of the catheter body.

Any of these devices may also include a drive shaft extending along thelength of the catheter body. For example, the drive shaft may comprise acable drive shaft having a distal gear configured to drive rotation ofthe cutting ring. In some variations, the annular cutting ring comprisesinternal gear teeth configured to mate with a drive shaft to rotate thecutting ring.

The drive shaft may be directly connected to the annular cutting ring.For example, the drive shaft comprises a hollow tubular drive shaft.

Any of the catheters described herein may include a guidewire lumenextending the length of the catheter. The lumen may be centered oroff-centered, and one or more additional lumens may also be included.

In some variations, the annular cutting ring may form an outer surfaceof the catheter in both the closed and open configurations.

The device may also include an internal tissue collection regionconfigured to receive tissue cut by the annular cutting ring. Forexample, the tissue collection region may be located within the distaltip assembly. The tissue collection region may be located within thecatheter body.

In some variations, the annular cutting ring may be displaceable withthe distal tip assembly. For example “pull to cut” embodiments, in whichthe tissue is cut as the catheter is withdrawn proximally, may includethe annular cutting ring on the displaceable distal tip. In somevariations the annular cutting ring remains in-line with the catheterbody when the distal tip assembly is displaced.

As mentioned, in any of these variations, the catheter may include anOCT imaging subassembly. For example, the OCT imaging subassembly mayinclude a fiber optic extending the length of the catheter body. The OCTimaging assembly may comprise a side-facing OCT emitting element fixedproximal to the annular cutting ring.

The OCT imaging assembly may include a side-facing OCT emitting elementfixed distally to the annular cutting ring.

Also described herein are atherectomy catheters for cutting tissuehaving a laterally displaceable tip. These devices may include: anelongate catheter body having a longitudinal axis; a laterallydisplaceable distal tip assembly; an annular cutting ring between thecatheter body and the distal tip assembly; and a distal tip controlconfigured to switch the distal tip assembly between a closedconfiguration, in which the distal tip assembly is in-line with thecatheter body, and an open configuration exposing a cutting edge of theannular cutting ring, in which the distal tip assembly is laterallydisplaced from the catheter body and parallel to the longitudinal axisof the catheter body.

Also described herein are atherectomy catheters for cutting tissuehaving a laterally displaceable tip, the devices having: an elongate,flexible catheter body having a proximal end and a distal end and alongitudinal axis; an elongate and laterally displaceable distal tipassembly; an annular cutting ring between the distal end of the catheterbody and the distal tip assembly forming an outer surface of theatherectomy catheter; and a distal tip control at the proximal end ofthe catheter that is configured to switch the distal tip assembly from aclosed configuration in which the distal tip assembly is in-line withthe catheter body, and an open configuration in which the distal tipassembly is laterally displaced from the catheter body and parallel tothe longitudinal axis of the catheter body, exposing a cutting edge ofthe annular cutting ring.

Also described herein are atherectomy catheters for cutting tissuehaving a laterally displaceable tip, including: an elongate catheterbody having a longitudinal axis; a laterally displaceable distal tipassembly; an annular cutting ring between the catheter body and thedistal tip assembly, wherein the cutting ring includes an internal gearsurface; a drive shaft extending the length of the catheter body havinga driving pinion gear for driving rotation of the annular cutting ring;and a distal tip control configured to switch the distal tip assemblybetween a closed configuration, in which the distal tip assembly isin-line with the catheter body, and an open configuration exposing acutting edge of the annular cutting ring, in which the distal tipassembly is laterally displaced from the catheter body and parallel tothe longitudinal axis of the catheter body.

The driving pinion gear and the internal gear surface of the annularcutting ring may be configured to provide a mechanical advantage forturning the annular cutting ring. The devices may also include aguidewire lumen extending the length of the catheter. In somevariations, the annular cutting ring forms an outer surface of thecatheter in both the closed and open configurations.

Also described herein are methods of performing an atherectomy to removetissue from within a vessel lumen using an atherectomy catheter having acatheter body with a longitudinal axis, an annular cutting ring and alaterally displaceable distal tip assembly, the method comprising:advancing the atherectomy catheter within a vessel lumen; exposing acutting edge of the annular cutting ring of the atherectomy catheter bylaterally displacing the distal tip assembly away from the longitudinalaxis of the catheter body so that the distal tip assembly is parallel tothe longitudinal axis of the catheter body; and driving the cutting edgeagainst a wall of the vessel lumen to remove tissue.

Any of these methods may also include the step of rotating the annularcutting ring while driving it against the wall of the vessel lumen. Theannular ring may be rotated by driving an internal gear within an innersurface of the annular ring. The method may also include the step ofimaging the tissue using an OCT imaging subassembly on the catheter.

The driving step may comprise pushing the catheter distally, and/orpulling the catheter proximally. Any of these methods may also includethe step of collecting cut tissue within an opening of the atherectomycatheter.

Also described herein are methods of performing an atherectomy to removetissue from within a vessel lumen using an atherectomy catheter having acatheter body, annular cutting ring and a laterally displaceable distaltip assembly, the method may include the steps of: advancing theatherectomy catheter within a vessel lumen while the distal tip assemblyis in-line with the catheter body of the atherectomy catheter so thatthe distal tip assembly and the catheter body have a common longitudinalaxis; laterally displacing the distal tip assembly to expose a cuttingedge of the annular cutting ring so that the longitudinal axis of thedistal tip assembly is parallel but laterally offset from thelongitudinal axis of the catheter body; and driving the cutting edgeagainst a wall of the vessel lumen while rotating the annular ring toremove tissue.

The annular ring may be rotated by driving an internal gear within aninner surface of the annular ring.

In some variations, the method further include the step of imaging thetissue using an OCT imaging subassembly on the catheter. In any of themethods described herein, the step of driving the catheter may includepushing the catheter distally and/or pulling the catheter proximally.Any of these methods may also include the step of collecting cut tissuewithin an opening of the atherectomy catheter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A-1H illustrates different examples of lateral displacement.

FIG. 2A is an isometric view of a catheter having a laterallydisplaceable distal tip region in a closed/non-activated configuration.

FIG. 2B is an isometric view of the catheter of FIG. 2A showing thedistal tip region laterally displaced.

FIG. 2C is a cross-sectional view of the catheter shown in FIG. 2B,above (in the open/laterally displaced configuration).

FIG. 2D is a side view of the catheter shown in FIG. 2B.

FIGS. 3A and 3B illustrate one variation of an actuation mechanism(which may be referred to as a “collar actuation method”) for opening(laterally displacing) and closing the distal tip assembly.

FIGS. 4A and 4B show isometric and face views of an off-axis drivingpinion gear and internal gear surface of the cutter body.

FIG. 5 illustrates a perspective view of a gear-driven annular cuttingring including internal gears and a D-bore pinion gear configuration.

FIG. 6 shows one example of a helical gear.

FIG. 7 illustrates, in principle, a bevel gear drive and cutter exposure

FIG. 8 shows one example of a catheter having a laterally displaceabledistal tip assembly and an OCT imaging fiber.

FIG. 9A is an isometric view of another variation of an atherectomycatheter having a laterally displaceable distal tip region in aclosed/non-activated configuration.

FIG. 9B is an isometric view of the catheter of FIG. 9A showing thedistal tip region laterally displaced.

FIG. 9C is a cross-sectional view of the catheter shown in FIG. 9B inthe open/laterally displaced configuration.

FIG. 9D is a side perspective view of the catheter shown in FIG. 9B.

FIG. 10A is an isometric view of another variation of an atherectomycatheter having a laterally displaceable distal tip region in aclosed/non-activated configuration.

FIG. 10B is an isometric view of the catheter of FIG. 10A showing thedistal tip region laterally displaced.

FIG. 10C is an enlarged perspective view of the junction between theannular cutting ring and rest of the catheter body of the device shownin FIG. 10A.

FIG. 10D is an enlarged perspective view of the junction between theannular cutting ring and rest of the catheter body of the device shownin FIG. 10B.

FIGS. 11A and 11B show annotated side perspective views of a cathetersuch as the one shown in FIGS. 10A-10D.

FIGS. 12A and 12B show cross-sectional views through a length ofcatheter such as the one shown in FIGS. 10A-10D.

FIG. 13 shows an embodiment of an atherectomy catheter including an OCTimaging system.

DETAILED DESCRIPTION OF THE INVENTION

In general the atherectomy devices described herein include laterallydisplaceable distal tip regions. FIG. 1A-1H illustrate examples oflateral displacement. As used herein, lateral displacement includesmovement of the distal tip region of a catheter from a first position inwhich the long axis of the distal tip region (the longitudinal axis ofthe distal tip region) is in-line with the long axis of the proximalbody of the catheter (the longitudinal axis of the catheter body) to asecond, laterally displaced, position in which the distal tip region hasshifted out plane so that the long axis of the distal tip region isparallel with the long axis of the catheter body, but in a differentplane. The terms “parallel” and “in line” in reference to the long orlongitudinal axis do not require that the catheter regions be straight.

FIGS. 1A and 1B, illustrate lateral displacement of a rectangular regionhaving a proximal 101 and distal 103 elements. In FIG. 1A, the proximal101 and the distal 103 regions are in-line, and share a commonlongitudinal (long) axis, which may be imagined as a horizontal axisthat passes through the midline of both rectangular regions. In FIG. 1B,the distal 103 element has been laterally displaced relative to theproximal 101 element, and has shifted upwards. Although the longitudinalaxis of the proximal 101 element and the longitudinal axis of the distal103 element are still approximately parallel, they are no longerin-line, but have separated by a radial distance.

FIGS. 1C and 1D illustrate another example, in which the proximal 101and distal 103 rectangular elements are laterally and slightlylongitudinally displaced. Similar examples of lateral displacement areillustrated for cylindrical shapes in FIGS. 1E to 1H. FIGS. 1E and 1Fshow lateral displacement of a proximal 105 and distal 107 elementsalong a plane perpendicular to the long axis. FIGS. 1G and 1H illustratelateral displacement of proximal 105 and distal 107 cylindrical elementsalong a non-perpendicular plane that (similar to FIGS. 1C and 1D) alsoresult in a slight longitudinal displacement.

FIGS. 2A-8B illustrate one variations of an atherectomy catheter devicehaving a laterally displaceable distal tip region. These variations areconfigured as gear-driven catheters, in which the cutter is an annularcutting ring that includes a sharp or cutting edge along one side, andincludes internal threads on the inner surface of the ring.

For example, FIG. 2A shows a distal portion of a device in a“non-activated” configuration, in which the distal tip region 201 isin-line with the catheter body 205 (or at least the region of thecatheter body adjacent to the distal tip region). FIG. 2B shows the samecatheter in an “activated” configuration. In the closed/non-activatedposition, the cutter 203 is protected and is not exposed, which mayprevent unintended damage to the inner diameter of ancillary medicaldevices and the vasculature. In the open/activated position, the distaltip assembly 201 is laterally displaced to expose up to 180 degrees ofthe cutter edge. When opened, the bottom circumference of the tipassembly increases the overall crossing profile (e.g., diameter) of thedevice. This enlarged configuration (the distance between bottom tipsurface and upper cutter edge) may extend the inner lumen of the vessel(e.g., artery) and create an opposing force for cutter engagement intothe tissue. This appositional force may ensure the purchase of thecutting edge against the targeted cutting site will be enough to bothengage the tissue and maintain contact during the cutting pass.

The tip actuation method shown in FIGS. 2A and 2B involves sliding apinion gear drive shaft relative to the cutter assembly. FIG. 2C is across-sectional view of the distal assembly of FIGS. 2A-2B. FIG. 2D isan annotated side view of the same device. As illustrated in thesefigures, as the pinion driveshaft is forced forward in the assembly 201,the proximal 60 degree mating faces and pin slots of the cuttingassembly adaptation and tip mechanism may force the tip forward (distal)and down. The angle and distance traveled by the tip may be modifiedwith different face angles and relative pin slot positions. Similar tipactuation methods may be accomplished by translating a collar proximalto the cutter assembly that is attached via a pin and slot design.Translation of this collar will actuate the assembly. An example of thismay be shown in FIGS. 3A and 3B.

As illustrated herein, the distal tip assembly or apposition element maybe laterally displaced and “drop” directly downward in plane with themain body of the catheter. This y-axis coincidence provides at least twobenefits: (1) deflection and/or a curved portion of the distal deviceassembly may cause rotational instability in tortuous vasculature as thedevice travels the path of least resistance (curve or deflectioncontinued alignment with bend/turn in the vessel); and (2) cutterapposition forces with a deflected tip configuration that may be appliedup and downstream of the cutting location, and may be defined byvascular characteristics potentially a long distance from the keytarget. This direct “downward” activation of the tip assembly ensuresthat an apposition force is applied local to the cutting assembly.Apposition force near directly 180 degrees of the cutter edge may makecertain that the target lesion define the amount of engagement betweencutter and tissue.

In addition, laterally displacing the distal tip assembly and/or cutterexposure with minimal longitudinal motion and no angular deflection ofthe tip mechanism may provide for the tissue entry window to be mainlydefined by the vertical distance from outer tip diameter to cutter edge.This may prevent increased tissue invagination into the exposed tissueentry point with increased apposition forces. Depth of cut may thenremain relatively constant at varied force of engagement between cutterand tissue providing the physician with a more predictable and safedevice.

Alternate methods of tip actuation may include using a worm gearanchored to a pinion gear driveshaft and rack anchored to the tipassembly. Rotation of the pinion gear drive shaft to rotate the cuttermay additionally advance and displace the tip. The direction of rotationmay be alternated to open and close the system. Alternatively, a balloonand/or inflatable lumen may be placed between the tip mechanism andcutting assembly adaptation such that inflation will push the tipmechanism off axis. Magnetic elements may also be used to actuate theassembly by taking advantage of the natural means of attraction orrepulsion or by preferentially applying an electrical current. Finally,as discussed below and represented in FIG. 6, helical gears may be usedfor the cutter body internal gears and pinion gear such that the pitchangle may be altered to provide an axial actuation force vector whendriving the cutter. In some variations, the distal tip assembly/regionmay be actuated by a push/pull tendon that extends the length of thecatheter.

In some variations, the apposition force for cutter engagement may beachieved by means of a balloon mounted on the circumference of thecatheter distal assembly, approximately 180 degrees from the cuttingplane. The inflation of this balloon would also increase the effectivesize of the device, distend the artery, and engage the cutter into thetissue. A highly lubricious base balloon material and/or hydrophiliccoating may be used such that the balloon may be in contact with thewall of the artery during the cutting traverse. The balloon may be madeof an elastic or inelastic material.

A “sponge” like material may also be used to preferentially appose thecutter in the same manner as the inflated balloon or lumen discussedabove. Exposing the porous and absorbent material to infused fluid orblood would expand the material and actuate the tip or directly applyforce to the wall of the artery. By extracting the fluid with negativepressure or mechanical compression the overall dimensions of theabsorber would be reduced to deactivate the system.

In the catheter variation shown in FIGS. 2C and 2D, the axis of theguide wire Lumen and Pinion Drive Shaft are aligned in both open andclosed positions of the distal tip assembly. This may ensure minimalsliding friction as the device is advanced and retracted over the wire.In some variations it may be advantageous to have the guidewire lumencrimp or bend on the guidewire.

FIGS. 4A and 4B illustrate one variation of a primary internal gearassembly with an approximate 2 to 1 gear ratio between internal cutterbody and pinion. The annular cutting ring 401 includes internal gearteeth (“female” teeth) 403 on the inner surface that is configured tomate with the driving pinion gear 405. The means for controlling theoffset of the internal and pinion gear axis is the supportingnon-spinning cutter bearing surface 407. This component may bemanufactured from a high grade engineering plastic or high wearcoefficient material. The annular “bean” shaped inner lumen may thusdefine a lumen or space for cut tissue to be stored or to travel throughin the catheter. This support component also isolates the gear teethfrom the tissue specimen. This component may also ensure an appropriateengagement force is maintained according to gear tooth profilerequirements.

As mentioned, in some variations, the pinion driveshaft translation mayused to actuate the tip. This pinion gear driveshaft may be anchoredlongitudinally to the pinion gear, as shown in FIG. 2D, or it may befree to translate relative to the pinion, as shown in FIG. 5. In thecase where the driveshaft slides relative to the pinion, an asymmetricmating x-section of the driveshaft and pinion gear may be present toensure proper torque transmission between components. In this example,the pinion gear may not be required to slide relative to the cutter bodywhile spinning.

As discussed above, a helical gear configuration may be used for thecutter driving assembly. A left-hand pitch angle on the cutter body, andmating pinion pitch would provide proximal thrust with clockwiserotation of the pinion. Relative longitudinal motion created by axialthrust can be used to actuate the distal tip. In addition, this proximalforce will seat the cutter within the mating assembly to ensure thecutting edge is predictably aligned with distal window defining andshearing edges. Finally, the helical configuration may provide more geartooth surface area engagement per length of assembly at each angularposition to ensure small gears have more opportunity to transmit therequired torque.

A bevel gear interaction may also be used to drive the cutter assembly.As shown in FIG. 7, a pinion bevel gear and driveshaft may remainconcentric to a fixed catheter axis and may translate along that axis.In some variations, the moving bevel pinion may be dome-shaped so thatthe grooves/teeth engage fully. A bevel gear and cutter edge assemblymay be fixed longitudinally relative to a main catheter body but be freeto move perpendicular to the mating bevel pinion axis. Translation ofthe pinion gear along its axis of rotation may change the position ofthe cutter relative to the catheter axis and consequently raise or lowerthe cutter to expose the cutting edge.

In any of these variations, the catheter device may also includeon-board and real time image guidance capabilities. This may include animaging element, or energy emitting assembly, positioned at the distalportion of the device such that local images of the vessel may guidedevice usage. One specific configuration of an OCT system that may beused for this distal imaging element is described in co-pendingapplications, including U.S. patent application Ser. No. 12/790,703,previously incorporated by reference. The distal energy emitter(s) maybe positioned in multiple locations in fixed positions or embodied in amating assembly that may translate in an eccentric lumen or in thehollow lumen of the driveshaft. The emitter may send and receiverelevant light or sound signals at 90 degrees from the catheter axis orat angles up to approximately 50 degrees to visualize distal or proximalwall features from a fixed position.

FIG. 8 shows one example of a catheter having a laterally displaceabledistal tip assembly and an OCT imaging fiber. The imaging fiber isconfigured for placement of the OCT sensing element 801 (the end of thefiber forming the “window”) just proximal to cutter body and positionedsuch that images are obtained in the cutting direction. The OCT sensingelement 801 is a side-facing element. In this example, the OCT window isfixed in position on the side, and angular survey mages of the adjacentvessel region may be taken by rotating the entire catheter around thevessel and/or moving it longitudinally as well. This image scanning maypreferably be done before laterally displacing the distal tip assembly.In some variation the sensor (window) is positioned in more distallocations, including in the displaceable distal tip, which may allowvisualization of the region ahead of tissue removal in push removaldevices.

The emitting element may be positioned distal and/or proximal to thecutter edge. Distal placement would provide information during a cuttingpass prior to the cutter interacting with the tissue and, therefore,allow the physician to stop or continue cutting as disease changes indepth and/or position. Proximal placement would also provide guidanceregarding cut quality, depth and cutting efficiency. FIG. 9 shows anexample of the energy emitting portion of the fiber optic assemblymounted proximal to the cutter edge and fixed on the cutting side of thecatheter main body.

Furthermore, the data collected at the distal end of the catheter, aftertransmitted and appropriately processed, may drive an automated means oftip actuation and cutter position. Increased amounts of disease detectedby the software may automatically increase tip axially offsetconsequently increasing cut depth and apposition force. Cutter speeds,gear ratios and torque inputs may be adjusted according to input fromthe imaging system.

FIGS. 9A-9D illustrate another variation of an atherectomy catheterhaving a laterally displaceable distal tip assembly as described herein.In this example, the annular cutting ring 903 is also positioned betweenthe distal tip assembly 901 and the rest of the catheter body 905. Theannular cutting ring also forms a portion of the outer surface of thecatheter, although the cutting edge is protected or “closed” by thedistal tip assembly as shown in FIG. 9A. In this embodiment, the annularcutting ring is directly coupled to the drive shaft, which is notgeared. The drive shaft may be a braided or solid tube which is bondedat the distal end to the annular cutting ring.

In FIGS. 9A and 9B, the distal portion of the catheter device is shownin the non-activated and activated positions, respectively. Thisembodiment is in many ways similar to the variations discussed above. Inthe closed/non-activated position the cutter is protected to preventunintended damage to the inner diameter of ancillary medical devices andvasculature. In the open/activated position the tip assembly is droppedto expose up to half of the cutter edge. When open, the bottomcircumference of the tip assembly increases the overall crossing profileof the device. This maximum dimension between bottom tip surface andupper cutter edge extends to the inner lumen of the artery and createsan opposing force for cutter engagement into the tissue. Thisappositional force may help ensure the position of the cutting edgeagainst the targeted cutting site will both engage the tissue andmaintain contact during the cutting pass.

The tip actuation method shown in FIGS. 9A-9D involves sliding the tipactuation mechanism relative to the cutter assembly. As the mechanism isadvanced distally in the assembly, the proximal angled mating faces andpin slots of the cutting assembly adaptation and tip mechanism force thetip forward (distal) and down. The angle and distance traveled by thetip may be modified with different face angles and relative pin slotpositions.

As before, the distal tip assembly thus laterally displaces (droppingdirectly downward in the figure), in parallel with the main body of thecatheter.

FIG. 9C shows a cross-section through the device of FIG. 9B (shown withthe laterally displaced distal tip assembly), and FIG. 9D is a labeledand annotated side perspective view. In this example, the catheter bodycontains the driveshaft mechanism, and also forms a proximal tissuestorage region which may be positioned within the drive shaft.

FIGS. 10A-13 illustrate another variation of an atherectomy catheterwith a laterally displaceable distal tip region. In this example, theatherectomy device is configured as a pull-cutter, so that the tissuemay be cut by positioning the device within the vessel, laterallydisplacing the distal tip assembly, and pulling the catheter proximallyto cut tissue from within the vessel.

For example, FIGS. 10A and 10 B show the distal region of theatherectomy catheter devices in both the non-activated and activatedpositions. In the closed/non-activated position shown in FIGS. 10A and10C, the cutter 1003 is protected by the closed distal tip assembly 1001and catheter body 1005 to prevent unintended damage to the innerdiameter of ancillary medical devices and vasculature. In theopen/activated position shown in FIGS. 10B and 10D, the tip assembly1001 is raised to expose up to half of the cutter 1003 edge. When open,the top circumference of the cutter 1003 and distal tip assembly 1001increases the overall crossing profile of the device. This maximumdimension between top of the cutter edge and the bottom of the catheterbody extends the inner lumen of the artery and creates an opposing forcefor cutter engagement into the tissue. This appositional force willensure the position of the cutting edge against the targeted cuttingsite will be enough to both engage the tissue and maintain contactduring the cutting pass

In the example shown in FIGS. 10A-10D, the annular cutting ring 1003moves with the distal tip assembly 1001 when the distal tip assembly islaterally displaced. Further, the distal tip assembly includes a storageregion 1205 (visible in FIGS. 12A-12B). Pulling the catheter afterlaterally displacing the cutter and distal tip region, e.g., in thedirection indicated by the arrow 1010 in FIG. 10B, may result in tissuebeing cut and moved into the tissue storage region in the distal tip.

FIGS. 11A and 11B are an annotated illustration of the catheter shown inFIGS. 10A-10D. This example is also a gear-driven atherectomy catheter,and may also include a drive system such as the one illustrated above(e.g., FIGS. 4A-5). Thus, the device may include gear teeth on an innersurface of the annular cutting ring and a pinion gear driveshaft. FIGS.12A and 12B show cross-sectional views through the variation of FIGS.10A-10D. As mentioned, the distal tissue collection region 1205 isapparent.

This variation of the device may also include on-board and real timeimage guidance capabilities, as mentioned above, and may include animaging element, or energy emitting assembly, to be positioned at thedistal portion of the device such that local images of the vessel mayguide device usage. The emitting element may be positioned distal and/orproximal to the cutter edge. Proximal placement would provideinformation during a cutting pass prior to the cutter interacting withthe tissue and, therefore, allow the physician to stop or continuecutting as disease changes in depth and/or position. Distal placementwould also provide guidance regarding cut quality, depth and cuttingefficiency.

Furthermore, the data collected at the distal end of the catheter, aftertransmitted and appropriately processed, may drive an automated means oftip actuation and cutter position. Increased amounts of disease detectedby the software may automatically increase tip axially offsetconsequently increasing cut depth and apposition force. Cutter speeds,gear ratios and torque inputs may be adjusted according to input fromthe imaging system.

For example, in FIG. 13, an OCT sensor/emitting element 1307 (which maycorrespond to the distal end of the optical fiber that forms part of theOCT system) is shown on the distal end of the catheter body 1305 device,immediately before the laterally displaceable annular cutting ring 1305and distal tip assembly 1301. This may allow for visualization of thematerial before cutting when pulling the catheter to cut.

Additional details pertinent to the present invention, includingmaterials and manufacturing techniques, may be employed as within thelevel of those with skill in the relevant art. The same may hold truewith respect to method-based aspects of the invention in terms ofadditional acts commonly or logically employed. Also, it is contemplatedthat any optional feature of the inventive variations described may beset forth and claimed independently, or in combination with any one ormore of the features described herein. Likewise, reference to a singularitem, includes the possibility that there are plural of the same itemspresent. More specifically, as used herein and in the appended claims,the singular forms “a,” “and,” “said,” and “the” include pluralreferents unless the context clearly dictates otherwise. It is furthernoted that the claims may be drafted to exclude any optional element. Assuch, this statement is intended to serve as antecedent basis for use ofsuch exclusive terminology as “solely,” “only” and the like inconnection with the recitation of claim elements, or use of a “negative”limitation. Unless defined otherwise herein, all technical andscientific terms used herein have the same meaning as commonlyunderstood by one of ordinary skill in the art to which this inventionbelongs. The breadth of the present invention is not to be limited bythe subject specification, but rather only by the plain meaning of theclaim terms employed.

What is claimed is:
 1. An atherectomy catheter device for cutting tissuein a vessel, the device comprising: an elongate, flexible catheter bodyhaving a proximal end and a distal end and a longitudinal axis; anelongate displaceable distal tip assembly; a rotatable annular cuttingring between the distal end of the catheter body and the distal tipassembly; a handle attached to the proximal end of the catheter, thehandle including a control that is configured to expose a cutting edgeof the annular cutting ring by displacing the distal tip assembly from aclosed configuration in which the distal tip assembly is in-line withthe catheter body to an open configuration in which the distal tipassembly is off-axis from the catheter body, wherein the rotatableannular cutting ring remains in-line with the distal end of the catheterbody when the distal tip assembly is displaced and forms a distalcutting edge at the distal end of the catheter body; a balloon mountedon a circumference of the catheter body approximately 180 degrees froman exposed portion of the distal cutting edge, the balloon configured toinflate to urge the exposed portion of the distal cutting edge into thetissue; and an Optical Coherence Tomography (OCT) imaging subassemblycomprising a fiber extending the length of the catheter body, a distalend of the fiber fixed in a position that is proximal to the distalcutting edge, wherein the OCT imaging subassembly is configured to berotated to obtain angular survey images of the vessel.
 2. The device ofclaim 1, further comprising a drive shaft extending along the length ofthe catheter body, wherein axial movement of the driveshaft moves thedistal tip assembly between the open and closed configurations.
 3. Thedevice of claim 2, wherein the drive shaft comprises a cable drive shafthaving a distal gear configured to drive rotation of the cutting ring.4. The device of claim 2, wherein the drive shaft is directly connectedto the annular cutting ring.
 5. The device of claim 2, wherein the driveshaft comprises a hollow tubular drive shaft having a hollow lumen, theoptical fiber extending within the hollow lumen.
 6. The device of claim1, wherein the annular cutting ring comprises internal gear teethconfigured to mate with a drive shaft to rotate the cutting ring.
 7. Thedevice of claim 1, further comprising a guidewire lumen extending thelength of the catheter.
 8. The device of claim 1, wherein the annularcutting ring forms an outer surface of the catheter in both the closedand open configurations.
 9. The device of claim 1, further comprising aninternal tissue collection region configured to receive tissue cut bythe annular cutting ring.
 10. The device of claim 9, wherein the tissuecollection region is located within the distal tip assembly.
 11. Thedevice of claim 9, wherein the tissue collection region is locatedwithin the catheter body.
 12. An atherectomy catheter device for cuttingtissue having a displaceable tip, the device comprising: an elongatecatheter body having a longitudinal axis; a displaceable distal tipassembly attached to a distal end of the catheter body; an annularcutting ring between the catheter body and the distal tip assembly; aninflatable element near the distal end of the catheter body configuredto displace the distal tip assembly relative to the elongate catheterbody when inflated; and a handle attached to the elongate catheter body,the handle including a control that is configured to switch the distaltip assembly between a closed configuration, in which the distal tipassembly is in-line with the catheter body and the cutter is protectedby the distal tip assembly, and an open configuration, in which thedistal tip assembly is displaced from the catheter body, by inflatingthe inflatable element to move the distal tip assembly away from thedistal end of the catheter body to expose a cutting edge of the annularcutting ring, wherein the annular cutting ring remains in-line with thedistal end of the catheter body when the distal tip is displaced andforms an exposed distal cutting edge at the distal end of the catheterbody, further wherein the inflatable element is positioned approximately180 degrees from the exposed distal cutting edge when the distal tip isdisplaced.
 13. The device of claim 12, further comprising a drive shaftextending along the length of the catheter body.
 14. The device of claim13, wherein the drive shaft comprises a cable drive shaft having adistal gear configured to drive rotation of the cutting ring.
 15. Thedevice of claim 13, wherein the drive shaft is directly connected to theannular cutting ring.
 16. The device of claim 13, wherein the driveshaft comprises a hollow tubular drive shaft.
 17. The device of claim12, wherein the annular cutting ring comprises internal gear teethconfigured to mate with a drive shaft to rotate the cutting ring. 18.The device of claim 12, further comprising a guidewire lumen extendingthe length of the catheter.
 19. The device of claim 12, wherein theannular cutting ring forms an outer surface of the catheter in both theclosed and open configurations.
 20. The device of claim 12, furthercomprising an internal tissue collection region configured to receivetissue cut by the annular cutting ring.
 21. The device of claim 20,wherein the tissue collection region is located within the distal tipassembly.
 22. The device of claim 20, wherein the tissue collectionregion is located within the catheter body.
 23. The device of claim 12,further comprising an OCT imaging subassembly.
 24. The device of claim23, wherein the OCT imaging subassembly comprises a fiber opticextending the length of the catheter body.
 25. The device of claim 23,wherein the OCT imaging assembly comprises a side-facing OCT emittingelement fixed proximal to the annular cutting ring.
 26. The device ofclaim 23, wherein the OCT imaging assembly comprises a side-facing OCTemitting element fixed distally to the annular cutting ring.